BAGHDAD — They were known as the Sahwa, or the Awakening Councils — Sunni militiamen who took extraordinary risks to side with U.S. troops in the fight against al-Qaida during the Iraq War. Once heralded as a pivotal step in the defeat of the bloody insurgency, the Sahwa later were pushed aside by Iraq's Shiite-led government, starved of political support and money needed to remain a viable security force.